The present invention relates to a magnetic head including a magnetic core in which an amorphous magnetic metallic thin film is caused to adhere to a high-resistance substrate.
No magnetic core materials have been provided to satisfy properties such as magnetic flux density, abrasion resistance, permeability in a high-frequency zone or the like. In particular, although materials having higher permeability in the high-frequency zone are oxide magnetic materials, these materials, when they are applied to magnetic heads used for high density recording, are not practical due to the low magnetic flux density. Also, the metallic magnetic materials do not provide higher permeability in the high-frequency zone due to eddy-current loss although they provide high saturation magnetic flux density. In addition, since the metallic materials have inferior abrasion resistance, the practical use of the metallic materials is difficult in devices such as a magnetic head, where the magnetic materials come in direct sliding contact. In the high frequency zone, the eddy-current loss prevails in the metallic materials and, thus, a substrate on which amorphous thin films are formed requires the selection of a high resistance material. Generally, the high-resistance material has inferior heat conduction properties and it is difficult to form the amorphous metallic thin films on the material. Furthermore, it is difficult to cause the amorphous films to firmly adhere to the material so that the amorphous films will not come off during a processing operation, a sliding operation or the like. In the conventional methods, the amorphous films can not be obtained due to excessively raised substrate temperatures, and the amorphous films might come off, during the thin film forming operation or the processing operation of the device, due to weaker adherence force between the substrate and the amorphous film. The present invention provides a magnetic head having excellent high-frequency characteristics wherein at least a portion of a magnetic core, which is brought into contact with a magnetic recording medium, is made of an amorphous magnetic metallic material having a high saturation magnetic flux density. To improve the high-frequency characteristics according to this invention, the amorphous metallic films are caused to firmly adhere through an oxidation film, etc., to the high-resistance substrate to provide the practical magnetic heads. Also, the composition equation of the amorphous magnetic metallic films is as follows: EQU T.sub.1-x G.sub.x 0.1.ltoreq.x.ltoreq.0.3
wherein T is at least one element selected from the iron family elements consisting of Fe, Co and Ni, and G is at least one element selected from the group consisting of semi-metals, group IVa elements and group Va elements.
Since the crystallization temperature of the amorphous magnetic metallic films is as relatively low as approximately 450.degree. C., the temperature of the substrate has to be kept low. Thus, since it is difficult to provide the amorphous films having smaller coercive force on the high-resistance substrate, in this invention, the manufacturing method with respect to the conditions for forming the amorphous magnetic metallic films will be described.
Conventionally, as the magnetic core material for a narrow track magnetic head, no materials have been provided to satisfy properties such as magnetic flux density, abrasion resistance, permeability in the high-frequency zone or the like. Thus, a conventional narrow track magnetic head of such construction as shown in FIGS. 1(A) and 1(B) has been widely used.
As shown in FIGS. 1(A) and 1(B), in the magnetic head, a magnetic head core 1 is composed of an oxide magnetic material such as a single crystal ferrite, multiple crystal ferrite or the like. A notch, which is formed in the head gap portion 4, is filled with a non-magnetic material 3 such as glass or the like, and a coil 2 is wound around the core 1.
The oxide magnetic material is generally superior in abrasion resistance. A notch is provided on the core and is filled with the glass or the like. Thus, a magnetic head having a narrower track and superior abrasion properties is achieved. However, the oxide magnetic material has a smaller saturation magnetic flux density as compared with an alloy magnetic material such as permalloy or the like. Thus, when a magnetic head made of an oxide magnetic material is used for recording on the magnetic recording medium having a high coercive force, a large amount of magnetic flux is required to flow, and thus the core is magnetically saturated, so that sufficient recording on the magnetic recording medium cannot be performed. Meanwhile, since the oxide magnetic material does not allow plastic working such as blanking or the like to be performed thereon, processing operations such as precision cutting, surface grinding or the like are required to obtain the core of the oxide magnetic material. In addition, the surface affected layers produced by machining have to be removed. Accordingly, the manufacturing process of the magnetic head becomes extremely complicated, thus resulting in a higher manufacturing cost of the magnetic head. Furthermore, when such material is used as the magnetic head, chipping or grain dropping is caused at the gap portion due to the fragile property of the material.
On the other hand, the alloy magnetic material has a superior magnetic property, but has an inferior abrasion resistance. Accordingly, when the alloy magnetic material is used as the magnetic head, a portion in contact with the magnetic recording medium is substantially deformed, with the result that the gap portion is disadvantageously magnetically short-circuited.